The National Park Service is proposing Papahanaumokuakea Marine National Monument as one of two initial U.S. nominees to the World Heritage List, which recognizes the most significant cultural and natural treasures on the planet.

It would be the first nominations by the United States in more than 15 years.

The other proposed nominee is Mount Vernon, Va., longtime home of George Washington and a well-preserved example of an 18th century plantation in the American South.

UNESCO World Heritage Sites are designated under the World Heritage Convention. Currently, 851 sites have been designated in 140 countries.

There are 20 World Heritage Sites in the United States, including Hawai'i Volcanoes National Park, the only other Hawai'i location, which was designated in 1987.

Papahanaumokuakea, designated a marine national monument in 2006, comprises a 1,200-mile string of islands and adjacent waters northwest of Kaua'i that represent the oldest example of island formation and atoll evolution in the world, according to the state and federal agencies that manage the area.

It is home to more than 7,000 marine species, a quarter of which are found nowhere else, and includes nearly pristine coral reefs, the world's largest nesting albatross colony, and primary habitat for critically endangered Hawaiian monk seals and threatened green turtles.

The Northwestern Hawaiian Islands also contain important archaeological sites and have great cultural and spiritual significance to Native Hawaiians, the agencies said. In more recent times, the area hosted European explorers, whalers, and communication and early aviation outposts.

One of the islands, Midway, was the scene of a June 1942 battle that is considered the turning point of World War II in the Pacific.

Interior Secretary Dirk Kempthorne in January announced a tentative list of 14 locations, including Papahanaumokuakea and Mount Vernon, that the United States intends to nominate over the next 10 years as World Heritage Sites, the first new list since 1982. This month, Papahanaumokuakea and Mount Vernon were selected as the first two to be prepared for formal nomination by the National Park Service.

The Hawai'i site, co-managed by the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, and the State of Hawai'i, is the only one on Kempthorne's list nominated for both its cultural and natural significance.

The two initial nominations are expected to be submitted to the World Heritage Center by Jan. 30, with the World Heritage Committee to consider them no earlier than the summer of 2010.

Other cultural nominees on Kempthorne's list include: civil rights movement sites in Birmingham and Montgomery, Ala.; sites in Dayton, Ohio, associated with the Wright Brothers' pioneering efforts in human flight; nine archaeological sites in Ohio containing monumental Native American ceremonial earthworks; buildings in Virginia associated with Thomas Jefferson; the Poverty Point National Monument and State Historic Site in Louisiana, comprising an ancient hunter-gatherer settlement; Franciscan missions in San Antonio, Texas; the prehistoric Serpent Mound in Ohio; and Frank Lloyd Wright buildings in seven states.

The four other nominated natural sites on the list are: Fagatele Bay National Marine Sanctuary, American Samoa; Okefenokee National Wildlife Refuge in Georgia; Petrified Forest National Park in Arizona; and White Sands National Monument in New Mexico.